Journal articles on the topic 'Blade-root'
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1
Sal, Firat. "Analysis of combined passively and actively morphing blade root chord length and blade taper for helicopter control." Aircraft Engineering and Aerospace Technology 92, no. 2 (November 4, 2019): 172–79. http://dx.doi.org/10.1108/aeat-04-2019-0077.
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Purpose The purpose of this study is to examine the effect of passive and active morphing of blade root chord length and blade taper on the control effort of the flight control system (FCS) of a helicopter. Design/methodology/approach Physics-based helicopter models, which are functions of passive and active morphing, are created and applied in helicopter FCS design to determine the control effort. Findings Helicopters, having both passively and actively morphing blade root chord length and blade taper, experience less control effort than the ones having either only passively morphing blade root chord length or only blade taper or only actively morphing blade root chord length and blade taper. Practical implications Both passively and actively morphing blade root chord length and blade taper can be implemented for more economical autonomous helicopter flights. Originality/value Main novelty of our article is simultaneous application of passive and active morphing ideas on helicopter root chord length and blade taper. It is also proved in this study that using both passive and active morphing ideas on helicopter blade root chord and blade taper causes much less energy consumption than using either only passive morphing idea on helicopter blade root chord and blade taper or only active morphing idea on helicopter blade root chord and blade taper. This also reduces fuel consumption and also makes environment cleaner.
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Sal, Firat. "Effects of the actively morphing root chord and taper on helicopter energy." Aircraft Engineering and Aerospace Technology 92, no. 2 (December 16, 2019): 264–70. http://dx.doi.org/10.1108/aeat-08-2019-0165.
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Purpose The purpose of this paper presents the effects of actively morphing root chord and taper on the energy of the flight control system (i.e. FCS). Design/methodology/approach Via regarding previously mentioned purposes, sophisticated and realistic helicopter models are benefitted to examine the energy of the FCS. Findings Helicopters having actively morphing blade root chord length and blade taper consume less control energy than the ones having one of or any of passively morphing blade root chord length and blade taper. Practical implications Actively morphing blade root chord length and blade taper can be used for cheaper helicopter operations. Originality/value The main originality of this paper is applying active morphing strategy on helicopter blade root chord and blade taper. In this paper, it is also found that using active morphing strategy on helicopter blade root chord and blade taper reasons less energy consumption than using either passively morphing blade root chord length plus blade taper or not any. This causes also less fuel consumption and green environment.
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Amer, Kenneth B. "Technical Notes: Comment on the “Minimum Weight Design of Helicopter Rotor Blades with Frequency Constraints,” Journal of the American Helicopter Society, October, 1989." Journal of the American Helicopter Society 35, no. 2 (May 1, 1990): 69. http://dx.doi.org/10.4050/jahs.35.2.69.
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It appears that most of the weight saving from the reference blade to the minimum‐weight blade is in the region of the blade root. Undoubtedly, the reference blade requires this weight increase to accommodate the usual bending fatigue loads at the root. The authors do not address the question of how their minimum‐weight blade would handle blade‐root fatigue loads.
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Zhou, Peng Zhan, and Fang Sheng Tan. "Stress Characteristics Analysis on a Composite Wind Turbine Blade." Advanced Materials Research 602-604 (December 2012): 111–14. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.111.
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The stress characteristics on a composite wind turbine blade are analyzed by using a finite element method. The whole stress level of the spar cap and the blade root is higher than that of the shear web and the airfoil plate, so the spar cap and the blade root are the main force-supporting parts. If the stress concentration point on the interface corner between the blade root and the shear web is neglected, the stress of the spar cap is higher than that of the blade root, and its maximum stress and mean stress are 211 MPa and 180 MPa respectively. The maximum stress of the blade is only 34.8% of the tensile stress of the glass-fiber/epoxy composites. It indicates that the laminate structural design of the blade is inclined to be safety.
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Wiryolukito, Slameto. "Design Flaw Enhanced by Improper Workmanship to Cause Fatigue Failure on Rotor Blade of Compressor Gas Turbine." Applied Mechanics and Materials 660 (October 2014): 593–97. http://dx.doi.org/10.4028/www.scientific.net/amm.660.593.
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Ten stages of Compressor Engine S/N 123 of X-Gas Turbine failed in service prior the schedule for overhaul at 40,000 hour. At the failure event the running hour was 29,600. The maintenance was normally done every 8000 hours including filter and gasket replacement, instrument re-calibration, and bore scope examination. Upon dismantling, it was found one blade at rotor stage #3 failed with facture surface strongly indicated a fatigue failure, defective on stator and rotor blades at downstream, no defective blades at upstream. Detail examination confirm Root Cause of failure on Compressor Blade of X-Gas Turbine were combination of a sharp radius of root chamfer as the major contributor and at lesser extent enhanced by “scratches” exist on root blade free surface. There was no evidences Foreign Objects or corrosion contributed to fail the compressor blades. Blade material was sound and did not contribute to fail the blade. The recommendations to avoid failure reoccurrences were all existing installed rotor blades shall be dismantled and examined for the existence of crack at their root area. Inspection on brand new blades for the existence of scratches on blade surface prior assembly shall be strongly imposed; blade with preexisting scratch shall be rejected. In a design stages, increase the sharp chamfer radius on blade root is worth-while to be analyzed further. Workmanship during blade assembly shall not develop any scratch on blade surface especially on its root surface. A procedure and schedule for inspection on the running blades shall be refined to be able to detect any crack on the operating blades; special attention shall be given on root area.
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Hee, Lim Meng, M. Salman Leong, and K. H. Hui. "Blade Faults Classification and Detection Methods: Review." Advanced Materials Research 845 (December 2013): 123–27. http://dx.doi.org/10.4028/www.scientific.net/amr.845.123.
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Blade faults are ranked among the most frequent causes for gas turbine failures. This paper provides a review on the types of blade faults as well as its pertinent detection methods. In this paper, blade faults are categorized into five major groups according to their nature and characteristics namely, blade rubbing, blade fatigue failures, blade deformation, blade fouling, and blade root related problems such as cracked root and loose blade. This paper aims to provide an overview on the characteristics of each type of blade fault as well as its best detection methods available to date.
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Dong, Zheng Yan, and Han Long Zhang. "Study on Finite Element Model of Bolt Strength in Blade Root." Applied Mechanics and Materials 427-429 (September 2013): 221–24. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.221.
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This study has established a 1/184 model of blade root by using finite element software (ANSYS), and analyzed the stress pipeline and errors of this blade root model. By transforming the loads in blade root and imposing axial step load, especially by analyzing models boundary conditions and the structure of contact surface, the axial stress, bending stress and the other parameters have been acquired.
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Oktay, Tugrul, and Firat Sal. "Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort." International Journal of Aerospace Engineering 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/6325269.
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In this study, the effect of simultaneous variation in blade root chord length and blade taper on the control effort of helicopter flight control system (i.e., FCS) of a helicopter is investigated. Therefore, helicopter models (i.e., complex, control-oriented, and physics-based models) including the main physics and essential dynamics are used. The effect of simultaneous variation in the blade root chord length and blade taper (i.e., in both chordwise and lengthwise directions dependently) on the control effort of an FCS of a helicopter and also on the closed-loop responses is studied. Comparisons in terms of the control effort and peak values with and without variations in the blade root chord and blade taper changes are carried out. For helicopter FCS variance-constrained controllers, specific output variance-constrained controllers are beneficial.
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Zhang, Yi, Ming Hui Zhang, and Yong Hui Xie. "Turbine Blade Straddle Root and Rim Structural Optimization Using Finite Element Contact Analysis." Advanced Materials Research 753-755 (August 2013): 1453–56. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.1453.
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The development of turbine blade root style is one of the key problems in the blade design technology as the root carries most of the loads of the whole blade. The optimal design problem and the corresponding numerical method were established for a straddle root structure with the minimum equivalent stress of the root and rim as the optimal objective. A multi-variable parametric model of the blade and rim, which took eight critical geometrical variables of the root and rim as design variables, was built by APDL (ANSYS parametric design language) and the optimal problem was numerically solved by combining pattern search algorithm with finite element method. The results indicate that the optimized structure has better strength performance, whose maximum equivalent stress of the root sharply decreased by 25.18% comparing with the original design. It eventually confirms the feasibility and validity of the proposed optimal design method.
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Li, Zhen, Bofeng Xu, Xiang Shen, Hang Xiao, Zhiqiang Hu, and Xin Cai. "Performance Analysis of Ultra-Scale Downwind Wind Turbine Based on Rotor Cone Angle Control." Energies 15, no. 18 (September 18, 2022): 6830. http://dx.doi.org/10.3390/en15186830.
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The theoretical feasibility of the power output strategy based on rotor cone angle control for ultra-scale downwind wind turbines is studied in this paper via the Open FAST simulation platform. The performance of five cases, namely UW, DW, DWC, DW6, and DW6IC, which have different rotor parameters or control strategies compared with the reference DTU 10 MW wind turbine, are calculated and analyzed. It is found that the downwind rotors have significant advantages in reducing the blade root load. The DW case reduces the peak load at the blade root by 22.54% at the cost of 1.57% annual energy production loss. By extending the length and redesigning the stiffness of the blade, the DW6 case achieves 14.82% reduction in the peak load at the blade root and 1.67% increase in the annual energy production under the same blade weight as that of the UW. The DWC case with rotor cone angle control has the same aerodynamic performance as the DW case with the same blade parameters. However, when the wind speed achieves or exceeds the rated speed, the blade root load decreases at a greater rate with the increasing wind speeds, and achieves minimum load with a wind speed of 16 m/s. Compared with the UW case, the DW6IC case with the improved rotor cone angle control reduces the peak load of the blade root by 22.54%, leading to an increase in annual energy production by 1.12% accordingly.
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Nurfauzi, Egi, Lilies Esthi Riyanti, and Bhima Shakti Arrafat. "Damage Analysis of Propeller Blade P/N R815505 with Root Cause Failure Analysis Method on ATR 72 Aircraft." Airman: Jurnal Teknik dan Keselamatan Transportasi 5, no. 2 (December 31, 2022): 87–94. http://dx.doi.org/10.46509/ajtk.v5i2.297.
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The propeller blade is a component that is the main source of thrust on the ATR 72 aircraft. Based on data from the Aircraft Flight Maintenance Log (AFML) for the period 2019 – 2021 ATR 72 aircraft, the propeller blade component was damaged causing the need for unscheduled removal which had impact losses to airlines such as delays and aircraft-on-ground (AOG). This study aims to find the root causes of damage to the propeller blade components. Analysis was carried out using the Root-Cause Failure Analysis (RCFA) method using fault tree analysis (FTA) and fishbone diagrams as tools so that factors related to propeller blade damage will be found. The results of analysis using fault tree analysis (FTA) and fishbone found that the root cause of damage to the propeller blade was in the area of the heating element (de-icer) as the top event, while the propeller blade operation, propeller blade maintenance and the ATR 72 aircraft operating environment were the intermediate events
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Weihing, Pascal, Tim Wegmann, Thorsten Lutz, Ewald Krämer, Timo Kühn, and Andree Altmikus. "Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine." Wind Energy Science 3, no. 2 (August 16, 2018): 503–31. http://dx.doi.org/10.5194/wes-3-503-2018.
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Abstract. The present study investigates flow dynamics in the hub region of a wind turbine focusing on the influence of nacelle geometry on the root aerodynamics by means of Reynolds averaged Navier–Stokes simulations with the code FLOWer. The turbine considered is a generic version of the Enercon E44 converter incorporating blades with flat-back-profiled root sections. First, a comparison is drawn between an isolated rotor assumption and a setup including the baseline nacelle geometry in order to elaborate the basic flow features of the blade root. It was found that the nacelle reduces the trailed circulation of the root vortices and improves aerodynamic efficiency for the inner portion of the rotor; on the other hand, it induces a complex vortex system at the juncture to the blade that causes flow separation. The origin of these effects is analyzed in detail. In a second step, the effects of basic geometric parameters describing the nacelle have been analyzed with the purpose of increasing the aerodynamic efficiency in the root region. Therefore, three modification categories have been addressed: the first alters the nacelle diameter, the second varies the blade position relative to the nacelle and the third comprises modifications in the vicinity of the blade–nacelle junction. The impact of the geometrical modifications on the local flow physics are discussed and assessed with respect to aerodynamic performance in the blade root region. It was found that increasing the nacelle diameter deteriorates the root aerodynamics, since the flow separation becomes more pronounced. Possible solutions identified to reduce the flow separation are a shift of the blade in the direction of the rotation or the installation of a fairing fillet in the junction between the blade and the nacelle.
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Verma, Amrit Shankar, Zhiyu Jiang, Zhengru Ren, Zhen Gao, and Nils Petter Vedvik. "Response-Based Assessment of Operational Limits for Mating Blades on Monopile-Type Offshore Wind Turbines." Energies 12, no. 10 (May 16, 2019): 1867. http://dx.doi.org/10.3390/en12101867.
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Installation of wind-turbine blades on monopile-type offshore wind turbines is a demanding task. Typically, a jack-up crane vessel is used, and blades are individually lifted from the vessel deck and docked with the preinstalled hub. During the process of mating, large relative motions are developed between the hub and root due to combined effects of wind-generated blade-root responses and wave-generated monopile vibrations. This can cause impact loads at the blade root and induce severe damages at the blade-root connection. Such events are highly likely to cause the failure of the mating task, while affecting the subsequent activities, and thus require competent planning. The purpose of this paper is to present a probabilistic response-based methodology for estimating the allowable sea states for planning a wind-turbine blade-mating task, considering impact risks with the hub as the hazardous event. A case study is presented where the installation system consisting of blade-lift and monopile system are modelled using multibody formulations. Time-domain analyses are carried out for various sea states, and impact velocities between root and hub are analyzed. Finally, an extreme value analysis using the Gumbel fitting of response parameters is performed and limiting sea state curves are obtained by comparing characteristic extreme responses with allowable values. It is found that the limiting sea states for blade-root mating tasks are low for aligned wind–wave conditions, and further increase with increased wind–wave misalignment. The results of the study also show that the parameter T p is essential for estimating limiting sea states given that this parameter significantly influences monopile vibrations during the blade-root mating task. Overall, the findings of the study can be used for a safer and more cost-effective mating of wind-turbine blades.
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Zhang, Ming Hui, Di Zhang, and Yong Hui Xie. "Design Optimization for Double-T Root and Rim of Turbine Blade with Three-Dimensional Finite Element Method." Applied Mechanics and Materials 215-216 (November 2012): 239–43. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.239.
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As the main bearing part in a turbine blade, the root carries most of the loads of the whole blade. The improvement of the root structure can be used to enhance the operation reliability of steam turbine. The research on design optimization for double-T root and rim of a turbine blade was conducted by three-dimensional finite element method. Based on the APDL (ANSYS parametric design language), a multi-variable parametric model of the double-T root and rim was established. Twelve characteristic geometrical variables of the root-rim were optimized to minimize the maximum equivalent stress. The optimal structure of the double-T root-rim is obtained through the optimization. Compared with the original structure, the equivalent stress level of the root and rim has a significant reduction. Specifically, the maximum equivalent stress of root and rim reduces by 14.25% and 13.59%, respectively.
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Damanik, Natalina, and Hendery Dahlan. "Failure Investigation and Crack Propagation Analysis of LP Blade Steam Turbine 220 MW." Key Engineering Materials 876 (February 2021): 67–76. http://dx.doi.org/10.4028/www.scientific.net/kem.876.67.
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The cracked blade in L-0, L-1 governor side, and L-1 generator side were found when A 220 MW low-pressure steam turbine was checked in the serious inspection. However, the crack population more dominant at L-1 Gen compared to L-0 Gov and L-1 Gov. Most of the cracks were located on 300-400 mm from the root of the blade span, and it did not associate with the pitting defect. In this study, the root cause of L-1 blade failure was investigated. There is three-stage of analyzing process, firstly capturing the airfoil and dimension of L-1—secondly, the material properties analysis, and finally stress analysis of L-1 by the finite element analysis software. L-1 is the blade with the chord length on the tip L-1 blade longer than root as 2.1% and the angle of an airfoil from root to tip twisted as 24 degrees. The type of material did not look precisely similar to AISI 422 because its hardness-strength is lower than AISI 422 as 5.1%. The finite element analysis shows that there was a symptom of the imprecise shroud gap that promoted maximum stress at 300-400 mm from the root area of the L-1 blade span. Moreover, a lack of hardness-strength material cannot accommodate the excessive movement of the blade and promoted the initial crack of L-1. A crack length blade as 16 mm shows a lower number of cyclic (Nf) to failure tremendously compared to standard blades such as 32,367 of the number cyclic for regular blade and 42.6 for the crack blade. Increasing 2 mm of initial crack will decrease significantly the number of cyclic Nf of the blade. It was tearing mode crack propagation of L-1 results a significant stress intensity factor compared to other modes, especially at 16 mm length of the crack.
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., Sutrisno, Prajitno ., Purnomo ., and B. W. Setyawan. "The Performance & Flow Visualization Studies of Three dimensional (3-D) Wind Turbine Blade Models." Modern Applied Science 10, no. 5 (April 2, 2016): 132. http://dx.doi.org/10.5539/mas.v10n5p132.
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<p>The researches on the design of 3-D wind turbine blades have been received less attention so far even though 3-D blade products are widely sold. In the opposite, advanced researches in 3-D helicopter blade have been studied rigorously. Researches in wind turbine blade modeling are mostly assumed that blade span wise sections behaves as independent two dimensional (2-D) airfoils, implying that there is no exchange of momentum in the span wise direction. Further more flow visualization experiments are infrequently conducted.</p><p>The purpose of this study is to investigate the performance of 3-D wind turbine blade models with backward-forward swept and verify the flow patterns using flow visualization. In this research, the blade models are constructed based on the twist and chord distributions following Schmitz’s formula. Forward and backward swept are added to the wind turbine blades. It is hoped that the additional swept would enhance or diminish outward flow disturbance or stall development propagation on the span wise blade surfaces to give better blade design.</p><p>The performance of the 3-D wind turbine system models are measured by a torque meter, employing Prony’s braking system, and the 3-D flow patterns around the rotating blade models are investigated applying “tuft-visualization technique”, to study the appearance of laminar, separated and boundary layer flow patterns surrounding the 3-dimentional blade system.</p>For low speed wind turbines, Dumitrescu and Cardos (2011) have identified that stall spreads from the root of the rotating blade. In this study, it is found that for blades with (i) forward swept tip and backward swept root, the initial stall at the blade bottom would be amplified by concurrent strengthening flow due to the backward swept root to create strong stall spreading outward, and therefore the blades gives lower performance. For blades with (ii) backward swept tip and forward swept root, the initial stall at the blade bottom would be weakened by opposite weakening flow due to the forward swept root, generate weak stall that tend to deteriorate. These blades have better performance.
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Gai, Feng, An Min Cai, Da Tong Zhang, and Li Xiang Sun. "Analysis on Influence of Effective Turbulence Intensity on Blade Root Fatigue Load of WTGS." Advanced Materials Research 538-541 (June 2012): 605–9. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.605.
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Based on the Palmgren-Miner linear cumulative fatigue damage theory, the blade root fatigue loads in different effective turbulence intensities were calculated and analysed. The results show that when the air density and the wind speed are constant, the blade root fatigue loads increase linearly with the effective turbulence intensity increasing, and the slopes increase linearly with the wind speed increasing. According to these results, the main source of the blade root fatigue loads under different wind conditions can be estimated to provide a theoretical basis for WTGS type selection in the special sites.
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Momin, M. Abdul, Paul A. Wempe, Tony E. Grift, and Alan C. Hansen. "Effects of Four Base Cutter Blade Designs on Sugarcane Stem Cut Quality." Transactions of the ASABE 60, no. 5 (2017): 1551–60. http://dx.doi.org/10.13031/trans.12345.
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Abstract. The cut quality of sugarcane stems during harvesting is of considerable importance, as any damage inflicted on the stems and root systems affects ratooning and reduces yield. In current conventional cutting systems for sugarcane, relatively little attention has been paid to optimizing the cutting dynamics by investigating various blade designs and configurations. One limitation of impact cutting methods is the relatively rapid blunting of the blade edges through wear, leading to stem damage. This study aimed at investigating the effects on sugarcane cut quality of four base cutter blade designs: a conventional straight blade, a 30° angled blade, a serrated blade, and a straight blade with laser cladding on its underside. Blades of each type were installed at a 45° angle on a base cutter fitted to a John Deere 3520 sugarcane harvester. Stem damage, root system damage, and stubble height were considered as cut quality indicators, and blade wear was evaluated as the percentage of metal mass loss after completing each harvesting operation. In this study, the extent of stem and root system damage was classified into nine categories: (1) undamaged stem, not uprooted, (2) undamaged stem, partially uprooted, (3) undamaged stem, uprooted, (4) partially damaged stem, not uprooted, (5) partially damaged stem, partially uprooted, (6) partially damaged stem, uprooted, (7) severely damaged stem, not uprooted, (8) severely damaged stem, partially uprooted, and (9) severely damaged stem, uprooted. The highest percentage of stems damaged during harvesting (approx. 38%) and the highest percentage of root systems damaged (approx. 36%) occurred with the angled blade. The percentages of undamaged stems for the straight, angled, serrated, and laser clad blades were 76.9%, 62.1%, 83.1%, and 72.3%, respectively; partially damaged stems were 11.25%, 21.97%, 11.29%, and 17.73%, respectively; and severely damaged stems were 11.9%, 15.9%, 5.65%, and 9.9%, respectively. Except for the angled blade, all the blades cut almost 80% of stems without affecting the root system, and only 5% of stems were uprooted. Indices for stem damage and uprooting damage were calculated to evaluate the cut quality on a scale from -1.00 (least damage) to +1.00 (greatest damage). For both indices, the serrated blade had values closest to the target value of -1.00, implying the least damage to stems and root systems. Greater stubble heights (110 mm) were observed for the angled blade, with 76% of cut stems above the target 75 mm threshold, which was selected based on the farmer’s suggestion. Comparatively less stubble height was obtained with the serrated and laser clad blades, and roughly 60% of stems were cut in the ideal range (<75 mm). Blade wear percentages per ha of harvested area, based on metal mass loss, were found to be 0.76% for the laser clad blade, 0.83% for the serrated blade, and 0.84% for the straight blade. No mass loss data were collected for the angled blade as it caused such a high level of stem damage that its test was discontinued. The results of this study classified the levels of stem and root system damage occurring in the field during harvesting and their effects on ratooning for four base cutter blade designs. Fundamental guidelines for optimal blade configurations associated with sugarcane harvesting are provided. Keywords: Blade wear, Stem damage, Stubble height, Sugarcane harvester.
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Malovrh, Brendon, and Farhan Gandhi. "Localized Individual Blade Root Pitch Control for Helicopter Blade—Vortex Interaction Noise Reduction." Journal of the American Helicopter Society 55, no. 3 (July 1, 2010): 32007–3200712. http://dx.doi.org/10.4050/jahs.55.032007.
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Rahimi, Javad, Esmaeil Poursaeidi, and Ehsan Khavasi. "Stress analysis of a second stage gas turbine blade under asymmetric thermal gradient." Mechanics & Industry 20, no. 6 (2019): 607. http://dx.doi.org/10.1051/meca/2019041.
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In this study the main causes of the failure of a GE-F9 second stage turbine blade were investigated. The stress distribution of the blade which has 6 cooling vents in three modes (with full cooling, closure of half of the cooling channels, and without cooling) was studied. A three dimensional model of the blade was built and the fluid flow on the blade was studied using the FVM method. The stress distribution due to centrifugal forces applied to the blade, temperature gradients and aerodynamic forces on the blade surface was calculated by the finite element model. The results show that the highest temperature gradient and as a result the highest stress value occurs for the semi-cooling state at the areas near the blade root and this status is true for the full cooling mode for the regions far from the root. However, the field observations showed that the failure occurred for the blade with the semi-cooling state (due to closure of some of the channels) at areas far from the root. It is discussed that the main factor of the failure is not the stress values being maximum because in the state of full cooling mode (the state with the maximum stress values) the temperature of the blade is the lowest state and as a result the material properties of the blade show a better resistance to phenomena like hot corrosion and creep.
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Verma, Amrit Shankar, Zhiyu Jiang, Zhengru Ren, Zhen Gao, and Nils Petter Vedvik. "Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment." Journal of Marine Science and Application 19, no. 2 (June 2020): 218–33. http://dx.doi.org/10.1007/s11804-020-00141-7.
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Abstract Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels. Despite the stable foundation of the lifting cranes, the mating process exhibits substantial relative responses amidst blade root and hub. These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions, which can cause impact loads at the blade root’s guide pin in the course of alignment procedure. Environmental parameters including the wind-wave misalignments play an important role for the safety of the installation tasks and govern the impact scenarios. The present study investigates the effects of wind-wave misalignments on the blade root mating process on a monopile-type offshore wind turbine. The dynamic responses including the impact velocities between root and hub in selected wind-wave misalignment conditions are investigated using multibody simulations. Furthermore, based on a finite element study, different impact-induced failure modes at the blade root for sideways and head-on impact scenarios, developed due to wind-wave misalignment conditions, are investigated. Finally, based on extreme value analyses of critical responses, safe domain for the mating task under different wind-wave misalignments is compared. The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub, aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact.
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Li, Yanjun, Yunhao Zheng, Fan Meng, and Majeed Koranteng Osman. "The Effect of Root Clearance on Mechanical Energy Dissipation for Axial Flow Pump Device Based on Entropy Production." Processes 8, no. 11 (November 20, 2020): 1506. http://dx.doi.org/10.3390/pr8111506.
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The axial flow pump is a low head, high discharge pump usually applicable in drainage and irrigation facilities. A certain gap should be reserved between the impeller blade root and the impeller hub to ensure the blade adjustability to broaden the high-efficiency area. The pressure difference between its blade surface induces leakage flow in the root clearance region, which decreases hydraulic performance and operational stability. Therefore, this study was carried out to investigate the effect of root clearance on mechanical energy dissipation using numerical simulation and entropy production methods. The numerical model was validated with an external characteristics test, and unsteady flow simulations were conducted on the axial flow pump under four different root clearance radii. The maximum reductions of 15.5% and 6.8% for head and hydraulic efficiency are obtained for the largest root clearance of 8 mm, respectively. The dissipation based on entropy theory consists of indirect dissipation and neglectable direct dissipation. The leakage flow in the root clearance led to the distortion of the impeller’s flow pattern, and the indirect dissipation rate and overall dissipation of the impeller increased with increasing root clearance radius. The inflow pattern in the diffuser was also distorted by leakage flow. The diffuser’s overall dissipation, indirect dissipation rate on the blade surface, and indirect dissipation rate near inlet increased with increasing root clearance radius. The research could serve as a theoretical reference for the axial flow pump’s root clearance design for performance improvement and operational stability.
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Sepehri Amin, H., Ahmad Kermanpur, Saeed Ziaei-Rad, Hassan Farhangi, and M. Mosaddeghfar. "An Investigation on Failure Analysis of Titanium Gas Turbine Compressor Blades." Materials Science Forum 561-565 (October 2007): 2241–44. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.2241.
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Several premature failures were occurred in the high-pressure section of an industrial gas turbine compressor due to the fracture of Titanium blade roots. In this work, the failure process of the compressor blades was investigated based on the experimental characterisation. Macro/microfractographic studies were carried out on the fracture surfaces. Optical and scanning electron microscopy of the blade airfoil and root were performed. Mechanical properties of the blade alloy were also evaluated and compared with the standard specifications. The experimental results showed no metallurgical and mechanical defects for the blade materials. Microstructures of the blade root and airfoil as well as the hardness and tensile properties were all comparable with those reported in the standard specification AMS 4928Q. Fractography experiments showed clearly multiple crack initiation sites and fatigue beach marks. Debris particles were observed on the fracture surface of samples and in the mouth of initiated cracks. The blade surface in contact to the disc in the dovetail region showed a higher surface roughness than the other surfaces. Based on the results obtained, the fretting fatigue mechanism was proposed for the premature failures. It was concluded that the stress concentration has been caused by either unsuitable curvature ratio of the disk dovetail, incorrect design of the blade or insufficient distance between the blade root and the disk in dovetail region.
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Dong, Guodan, Jianhua Qin, Zhaobin Li, and Xiaolei Yang. "An Inverse Method for Wind Turbine Blade Design with Given Distributions of Load Coefficients." Wind 2, no. 1 (March 10, 2022): 175–91. http://dx.doi.org/10.3390/wind2010010.
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It is shown in the literature that wind turbine designs with different load distributions have different wake features. To systematically study how different load distributions affect turbine wakes, a method for designing variants of blades with different radial load distributions, but with approximately the same power (CP) or thrust coefficient (CT), is needed. In this work, an inverse design method based on the blade element momentum method and the multi-dimensional Newton’s method, with the normal and tangential force coefficients as the design objective and iterations for satisfying the CP or CT constraint, is developed. The proposed method is validated using the two-bladed small-scale NREL phase VI S809 wind turbine blade design and the three-bladed utility-scale NREL 5 MW wind turbine blade design. Four variants of the NREL 5 MW wind turbine, i.e., the Root-CP, Tip-CP, Root-CT, and Tip-CT designs, which represent the variants of the original design (NREL-Ori) with a higher load near the blade root and tip regions with approximately the same power coefficient (CP) or thrust coefficient (CT) as that of the NREL-Ori design, respectively, are then designed using the proposed method. At last, the flapwise blade bending moment and the power coefficients from different variants of the NREL 5 MW turbine are compared for different tip speed ratios, showing that the “Root” designs are featured by a wider chord near the root, lower blade bending moment, and higher power coefficients for tip-speed ratios greater than nine.
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Hu, Hao, Xin-kai Li, and Bo Gu. "Flow Characteristics Study of Wind Turbine Blade with Vortex Generators." International Journal of Aerospace Engineering 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/6531694.
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The blade root flow control is of particular importance to the aerodynamic characteristic of large wind turbines. The paper studies the feasibility of improving blade pneumatic power by applying vortex generators (VGs) to large variable propeller shaft horizontal axis wind turbines, with 2 MW variable propeller shaft horizontal axis wind turbine blades as research object. In the paper, three cases of VGs installation are designed; they are scattered in different chordwise position at the blade root, and then they are calculated, respectively, with CFD method. The results show that VGs installed in the separation line upstream, with the separation line of the blade root as a benchmark, show a better effect. Pneumatic power of blades increases by 0.6% by installing VGs. Although the effect on large wind turbines is not obvious, there is a space for optimization.
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Chai, Bao Tong, Zheng Feng Wu, and Dong Xing Zhang. "Static Frequency Test and Leaf Fracture Analysis of Turbine Blades in a Power Plant." Applied Mechanics and Materials 893 (July 2019): 45–51. http://dx.doi.org/10.4028/www.scientific.net/amm.893.45.
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During the overhaul of a steam turbine of a power station, the frequency of the last twostages of the low-pressure rotor is tested and high-pressure rotor-regulated stage broken blades weresubjected to macroscopic inspection and analysis, chemical composition analysis, hardness test andmetallographic microstructure observation and analysis.The results of blade frequency measurementshow that the two stages of the low-pressure rotor can be safely and stably operated at the workingspeed. The results of broken blade analysis show that: due to the surface damage in the innersurface of the blade root, the blade vibration is aggravated, and the lower step of the concavegroove of the blade root is the stress concentration zone, where the fatigue crack source is generatedand gradually expanded, resulting in fatigue fracture of the blade; The fracture fatigue source zoneand the fatigue crack growth zone occupy approximately two-thirds of the entire fracture area,indicating that the blade fracture is a high-cycle fatigue fracture.
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Lin, Yuansheng, Yuqi Wang, and Yonghui Xie. "Steady-state stress analysis in a supercritical CO2 radial-inflow impeller using fluid solid interaction." Thermal Science 21, suppl. 1 (2017): 251–58. http://dx.doi.org/10.2298/tsci17s1251l.
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According to the geometry and the state parameters, a single channel model of a supercritical CO2 radial-inflow turbine is established. The finite volume method, the finite element method, and the shear stress transport turbulence model are used for solid-fluid interaction. In 3-D finite element analysis, the results of flow analysis and thermal analysis are adopted to obtain the stress distribution of the impeller in working condition. The results show that the maximum equivalent stress of the impeller is 550 MPa, which is located at the blade root of trailing edge and lower than the yield limit. Meanwhile, the centrifugal load increases the stress level on the inside back end surface and the surface of the blade root. The aerodynamic load causes obvious stress concentration at the blade root of the trailing edge and increases the stress level in the downstream position of the impeller. The thermal load increases the stress level on the outside edge of the back-end surface and the surface near the blade root of the leading edge.
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Antony Harison, M. C., M. Swamy, A. H. V. Pavan, and G. Jayaraman. "Root Cause Analysis of Steam Turbine Blade Failure." Transactions of the Indian Institute of Metals 69, no. 2 (November 26, 2015): 659–63. http://dx.doi.org/10.1007/s12666-015-0750-2.
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Major, D., M. Churchfield, and S. Schmitz. "Fatigue study of an inverse-designed low induction rotor using open-source tools." Journal of Physics: Conference Series 2265, no. 4 (May 1, 2022): 042034. http://dx.doi.org/10.1088/1742-6596/2265/4/042034.
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Abstract The current trend in wind turbine design leans toward increasing rotor diameter for increased energy capture. This presents a notable fatigue concern as blade loads increase with blade length. One solution to potentially alleviate the additional blade loading and improve the fatigue behavior of large-diameter wind turbines, while also reducing overall cost of energy, is the low-induction rotor. The purpose of this work is to perform a holistic analysis to assess the attainable benefits of a notional low-induction rotor variant of the DTU 10MW Reference Wind Turbine using multi-disciplinary open-source design and analysis tools. The notional low-induction rotor blade is designed using an inverse-design routine that allows for the direct specification of desired blade properties. To assess viability of the new rotor design, annual energy production and levelized cost of energy are considered along with fatigue at the blade root and the associated drivetrain and tower response to changes in blade loading. It is estimated that the proposed early-concept low-induction rotor design improves annual energy production by 6.35% (or 3 GW-h), resulting in a 4% (0.25 ¢/kW-h) reduction in levelized cost of energy. The low-thrust nature of the low-induction rotor design reduces root flap bending moment fatigue by up to 21.5%, and it is proposed that changes in blade root edgewise fatigue for the longer, heavier blades of the low-induction rotor can be alleviated with mass redistribution.
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Wang, Jiao, Yue-hao Zhang, Tao Yu, and Qing-kai Han. "Dynamic Characteristics of Blade with Viscoelastic Damping Block Based on Complex Eigenvalue Method." Shock and Vibration 2018 (2018): 1–16. http://dx.doi.org/10.1155/2018/5068901.
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A novel method for vibration suppression is proposed, adding a viscoelastic damping block to the root of the blade. The dynamical equation for a rotational viscoelastic damping block-blade (VE-blade) in a centrifugal force field and aerodynamic force field is established to calculate the dynamical natural frequency and responses of the VE-blade. Complex modulus model is applied to represent the constitutive law of viscoelastic material and shear force acting on the VE-blade formulates the effect of viscoelastic damping at the root interfaces. The dynamical equation of the system is established and the Galerkin method is used to discretize the partial differential equations to a 3-DOF system so as to compute the dynamic natural frequencies and responses of the VE-blade. Then the differential equations of motion with 3-DOF are numerically solved by using complex eigenvalue method. A cantilever VE-blade is simplified according to testing the first three natural frequencies of the real blade to obtain geometric parameters of cantilever beam. The effects of various parameters including thickness, storage modulus, loss factor of viscoelastic damping block, and rotating speed on natural frequency and modal damping ratio of VE-blade are discussed in detail.
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Lampart, Piotr. "Control of LP turbine rotor blade underloading using stator blade compound lean at root." Journal of Thermal Science 9, no. 2 (June 2000): 115–21. http://dx.doi.org/10.1007/s11630-000-0004-3.
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Anusonti-Inthra, P., F. Gandhi, and L. Miller. "Reduction of helicopter vibration through cyclic control of variable orifice dampers." Aeronautical Journal 107, no. 1077 (November 2003): 657–72. http://dx.doi.org/10.1017/s0001924000013531.
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Abstract The present study demonstrates that cyclically varying the damping coefficient of controllable lag and flap dampers can reduce the 4/rev vibratory hub loads of a four-bladed hingeless rotor helicopter in high speed forward flight. Gradient-based optimization is used to determine the optimal multi-cyclic damping variation inputs that minimise a composite vibration index comprising of all six components of vibratory hub loads. Optimal 2/rev and 3/rev variations in the lag damping coefficient virtually eliminate the vibratory hub drag force and yawing moments, and produce small reductions in the vibratory hub side force. The optimal lag damping variations, interestingly, produce increases in the 3/rev and 5/rev components of the blade root drag shear, that cancel the contributions of the blade root radial shear to the vibratory in-plane hub forces. Despite some increases in higher harmonics of blade response, damper loads, and blade and flexbeam root loads, the lower harmonics and the peak-to-peak values show little change, implying that blade and damper fatigue life would not be adversely affected. When optimal 2/rev and 3/rev variations in flap damping coefficient are introduced in conjunction with the optimal lag damping variations, 30% reductions in the hub vertical vibrations are obtained, in addition to the previous reductions in the vibratory in-plane forces and yawing moment. The cyclic flap damping variations reduce the higher harmonics of the blade root vertical shear. Reductions in hub vibration levels are obtained over a range of forward flight speeds.
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Dalli, Uğbreve;ur, and Şcedilefaatdin Yüksel. "Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps." Shock and Vibration 18, no. 5 (2011): 727–45. http://dx.doi.org/10.1155/2011/675791.
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An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.
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Sheard, A. G. "The Effects of Inlet Box Aerodynamics on the Mechanical Performance of a Variable Pitch in Motion Fan." Advances in Acoustics and Vibration 2012 (December 25, 2012): 1–10. http://dx.doi.org/10.1155/2012/278082.
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This paper describes research involving an in-service failure of a “variable pitch in motion” fan’s blade bearing. Variable pitch in motion fans rotate at a constant speed, with the changing blade angle varying the load. A pitch-change mechanism facilitates the change in blade angle. A blade bearing supports each blade enabling it to rotate. The author observed that as the fan aerodynamic stage loading progressively increased, so did the rate of blade-bearing wear. The reported research addressed two separate, but linked, needs. First, the ongoing need to increase fan pressure development capability required an increase in fan loading. This increase was within the context of an erosive operating regime which systematically reduced fan pressure development capability. The second need was to identify the root cause of blade-bearing failures. The author addressed the linked needs using a computational analysis, improving the rotor inflow aerodynamic characteristics through an analysis of the inlet box and design of inlet guide vanes to control flow nonuniformities at the fan inlet. The results of the improvement facilitated both an increase in fan-pressure-developing capability and identification of the root cause of the blade-bearing failures.
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Lin, Jinbao, Yanjuan Jin, Zhu Zhang, and Xiaochao Cui. "Strength Analysis of the Carbon-Fiber Reinforced Polymer Impeller Based on Fluid Solid Coupling Method." Mathematical Problems in Engineering 2014 (2014): 1–3. http://dx.doi.org/10.1155/2014/803261.
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Carbon-fiber reinforced polymer material impeller is designed for the centrifugal pump to deliver corrosive, toxic, and abrasive media in the chemical and pharmaceutical industries. The pressure-velocity coupling fields in the pump are obtained from the CFD simulation. The stress distribution of the impeller couple caused by the flow water pressure and rotation centrifugal force of the blade is analyzed using one-way fluid-solid coupling method. Results show that the strength of the impeller can meet the requirement of the centrifugal pumps, and the largest stress occurred around the blades root on a pressure side of blade surface. Due to the existence of stress concentration at the blades root, the fatigue limit of the impeller would be reduced greatly. In the further structure optimal design, the blade root should be strengthened.
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Mezaal, Naji Abdullah, Osintsev K. V., and Alyukov S.V. "The Computational fluid dynamics Performance Analysis of Horizontal Axis Wind Turbine." International Journal of Power Electronics and Drive Systems (IJPEDS) 10, no. 2 (June 1, 2019): 1072. http://dx.doi.org/10.11591/ijpeds.v10.i2.pp1072-1080.
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<span lang="EN-US">Computational fluid dynamics (CFD) simulations were performed in the present study using ANSYS Fluent 18.0, a commercially available CFD package, to characterize the behaviour of the new HAWT. Static three-dimensional CFD simulations were conducted. The static torque characteristics of the turbine and the simplicity of design highlight its suitability for the GE 1.5xle turbine. The major factor for generating the power through the HAWT is the velocity of air and the position of the blade angle in the HAWT blade assembly. The study presents the effect of The blade is 43.2 meters long and starts with a cylindrical shape at the root and then transitions to the airfoils S818, S825 and S826 for the root, body and tip, respectively. This blade also has pitch to vary as a function of radius, giving it a twist and the pitch angle at the blade tip is 4 degrees. This blade was created to be similar in size to a GE 1.5xle turbine by Cornell University [1]. In addition, note that to represent the blade being connected to a hub, the blade root is offset from the axis of rotation by 1 meter. The hub is not included in our model. The experimental analysis of GE 1.5xle turbine, so that possible the result of CFD analysis can be compared with theoretical calculations. CFD workbench of ANSYS is used to carry out the virtue simulation and testing. The software generated test results are validated through the experimental readings. Through this obtainable result will be in the means of maximum constant power generation from HAWT.</span>
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Hannun, Rafid M., Hazim I. Radhi, and Noura A. Essi. "The types of mechanical and thermal stresses on the first stage rotor blade of a turbine." Innovaciencia Facultad de Ciencias Exactas Físicas y Naturales 7, no. 1 (October 25, 2019): 1–11. http://dx.doi.org/10.15649/2346075x.513.
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Introduction: In this paper, the simulation of first stage of low pressure turbine for Nasiriya Power Plant was done to study the aerodynamic characteristic of steam along stage at load 70 MW, also the two types of mechanical stresses on the first stage rotor blade were studied in this paper. Materials and Methods:The material of blade was X20Cr13 stainless steel grade 1.4021. The first type of mechanical stresses which due to the steam pressure on the blade was analyzed. The seconds types of mechanical stresses that the centrifugal stresses on the blade. The AutoCAD software code was used for modeling the turbine stage, the dimensions and operational conditions were obtained practically from Nasiriya power plant and ANSYS (15.0) software was used to make simulate the turbine. Results and Discussion: The results showed that maximum steam velocity occurred at trailing edge of stationary blades and leading edge of rotating blades, also the maximum stresses occurred at the leading edge and trailing edge of root blade, the stresses due to the effect of centrifugal force is larger than the stresses due the pressure force. Conclusions: The maximum deformation occurred at tip of blade and minimum deformation depicted at root of blade.
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Kumar, M. Rohin, and C. Venkatesan. "Effects of blade configuration parameters on helicopter rotor structural dynamics and whirl tower loads." Aeronautical Journal 120, no. 1224 (February 2016): 271–90. http://dx.doi.org/10.1017/aer.2015.11.
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ABSTRACTThe influence of the blade geometric parameters on the structural dynamic characteristics, response and loads of a helicopter rotor under hover condition in a whirl tower was investigated. A general geometry was considered for the rotor blade which included configuration parameters like root offset, torque offset, pre-twist, pre-cone, pre-droop, pre-sweep, tip-sweep and tip-anhedral. The option of placing concentrated masses at any location on the blade was also included. Natural frequencies and the corresponding mode shapes of the rotating blade were obtained by solving the linear, undamped structural dynamics model in the finite element domain. For calculating the response and loads on the rotor, the complete aeroelastic equation was solved in modal space. Aerodynamic models used in the aeroelastic loads calculations were Peters-He dynamic wake theory for inflow and themodifiedONERA dynamic stall theory for airloads calculations. From the study, the blade structural dynamic characteristics are found to be sensitive to variation in blade geometric parameters. Tip-sweep was found to have significant effects on root oscillatory moments. The moments at the tip junction with the straight portion of the blade were found to be substantially affected by tip-sweep and tip-anhedral.
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Zhang, Ming Hui, Qiang Zhang, Lu Zheng, and Di Zhang. "Research on Three-Dimensional Structure Optimization for Fir-Tree Root and Rim of Turbine Blade with Complex Damping Structure." Applied Mechanics and Materials 312 (February 2013): 55–59. http://dx.doi.org/10.4028/www.scientific.net/amm.312.55.
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The research on structure optimization for the fir-tree root and rim of a steam turbine blade with complex damping structure was conducted by three-dimensional contact finite element method and mathematical optimization algorithm. A multi-variable parametric model of three turbine blades and rims with fir-tree root and rim was established. Twelve critical geometrical variables of the root-rim were optimized to minimize the maximum equivalent stress of the root-rim. The optimal structure of the fir-tree root-rim was finally obtained through the optimization process and the equivalent stress of the root and rim both had evident reductions, Compared with the initial structure, the maximum equivalent stress of the root and rim reduced by 13.47% and 12.26%, respectively. Relevant work is expected to support the design of turbine blade root-rim in theory and improve the operation reliability of turbo-machinery to some extent.
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Yardimoglu, Bulent, and Daniel J. Inman. "Coupled Bending-Bending-Torsion Vibration of a Rotating Pre-Twisted Beam with Aerofoil Cross-Section and Flexible Root by Finite Element Method." Shock and Vibration 11, no. 5-6 (2004): 637–46. http://dx.doi.org/10.1155/2004/702380.
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The purpose of this paper is to extend a previously published beam model of a turbine blade including the centrifugal force field and root flexibility effects on a finite element model and to demonstrate the performance, accuracy and efficiency of the extended model for computing the natural frequencies. Therefore, only the modifications due to rotation and elastic root are presented in great detail. Considering the shear center effect on the transverse displacements, the geometric stiffness matrix due to the centrifugal force is developed from the geometric strain energy expression based on the large deflections and the increase of torsional stiffness because of the axial stress. In this work, the root flexibility of the blade is idealized by a continuum model unlike the discrete model approach of a combination of translational and rotational elastic springs, as used by other researchers. The cross-section properties of the fir-tree root of the blade considered as an example are expressed by assigning proper order polynomial functions similar to cross-sectional properties of a tapered blade. The correctness of the present extended finite element model is confirmed by the experimental and calculated results available in the literature. Comparisons of the present model results with those in the literature indicate excellent agreement.
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Zhou, Qin, and Wei Zhao. "Stress State of Turbine Blade Root and Rim Considering Manufacturing Variations." Applied Mechanics and Materials 492 (January 2014): 56–59. http://dx.doi.org/10.4028/www.scientific.net/amm.492.56.
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Three-dimensional thermoelastic analysis on the fir-tree root and rim of the I-P cylinder’s first stage blade was performed in two cases of load condition: only centrifugal force and both centrifugal force and temperature load, and five different manufacturing variations were taken into account. The results show that: with high temperature, the stress level of root which is well-designed under room temperature increase obviously, and the load of the four root teeth is unevenly distributed. Moreover, manufacturing variation between contact surfaces lead to serious stress concentration and extremely high stress, and load distribution of the four root teeth is completely uneven. In addition, the influence of temperature on the stress distribution of blade root and rim is much different with different manufacturing variations.
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Bechly, M. E., and P. D. Clausen. "The Dynamic Performance of a Composite Blade from a 5kW Wind Turbine Part II: Predicted Blade Response." Wind Engineering 26, no. 5 (September 2002): 273–86. http://dx.doi.org/10.1260/030952402321160589.
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This paper presents analytical and computational predictions of the performance of an operating 2.5 m long composite wind turbine blade and compares these predictions with the results of detailed measurements. Part 1 of this paper describes in detail the important aspects of the 5 kW wind turbine, the experimental equipment and data acquisition procedures and presents and discusses some of the results from the experimental data. Here the analytical methodology of Eggleston and Stoddard (1987) and the solutions from the computational wind turbine software package Bladed, were used to predict the performance of the blade for a particular set of experimental conditions. The solutions of Eggleston and Stoddard, where only the first order dynamic equations of a simplified blade model are solved, underestimate the root flapwise moment, streamwise blade tip deflection and lead-lag tip deflection, but gave fairly accurate predictions for the blade lead lag moment. The turbine's structural dynamics within Bladed used a more accurate model of the blade and solved the structural dynamic equations by implementing modal analysis. The results gave root flapwise moment of the same order as those determined from the measurements, close agreement with the measured lead-lag moment, a slight underprediction of the flapwise tip deflection and large under prediction of the lead-lag tip deflection. The under prediction of the lead-lag deflection by both methods is likely to be due to the uncoupling of the lead-lag and flapping motions, and the unusual shape of the blade close to its root connection.
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Moynihan, Bridget, Babak Moaveni, Sauro Liberatore, and Eric Hines. "Estimation of blade forces in wind turbines using blade root strain measurements with OpenFAST verification." Renewable Energy 184 (January 2022): 662–76. http://dx.doi.org/10.1016/j.renene.2021.11.094.
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Augusto, G. L., A. B. Culaba, and W. H. Chen. "Identification of cumulative damage at the blade root of AB92 blade using Palmgren-Miner’s rule." IOP Conference Series: Earth and Environmental Science 463 (April 7, 2020): 012125. http://dx.doi.org/10.1088/1755-1315/463/1/012125.
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Sunar, M., and B. O. Al-Bedoor. "Vibration Measurement of Rotating Blades Using a Root Embedded PZT Sensor." Shock and Vibration 15, no. 5 (2008): 517–41. http://dx.doi.org/10.1155/2008/494639.
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Finite element and experimental studies are carried out to test the suitability of a piezoelectric (PZT) sensor in measuring vibrations of blades modeled as beams. The rotating system contains twelve blades mounted to the shaft through a rotor. The PZT sensor is secured in the root between the rotor and blade. First, finite element results are obtained using the finite element package ANSYS. A modal analysis is performed on the system to identify modes and mode shapes. Transient, harmonic and steady-state responses are then computed to test the ability of the PZT sensor in generating signals for blade vibrations. For the experimental part, the blade vibration signals are produced using the PZT sensor and a strain-gage, and the outputs are compared with each other. From both the finite element and experimental results, it is concluded that the root-embedded PZT sensor can be effectively used for blade vibration measurements in a wide range of cases.
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Suzanne Ahmad Radwan Masri, Kheir Eddine Tarsha Kurdi, Ahmad, Suzanne Ahmad Radwan Masri, Kheir Eddine Tarsha Kurdi, Ahmad. "Simulating NACA Equations Used in Optimizing Wind Turbine Blade Design: محاكاة معادلات NACA واستخدامها لتحسين تصميم شفرة العنفة الريحية." Journal of engineering sciences and information technology 5, no. 4 (December 30, 2021): 164–52. http://dx.doi.org/10.26389/ajsrp.n100521.
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Aerodynamic scientists are interested in geometry definition and possible geometric shapes that would be useful in design. This paper illustrates a simulation of a NACA four digits airfoil blade profile using MATLAB. As airfoil design became more sophisticated, this basic approach has been modified to include additional variables, and suggestions for the chord line length at the root and at the end of the blade. as well as changes in the twisting angle of the blade and its thickness, this helps to reduce the weight of the blade significantly Simulating NACA equations is very useful in obtaining coordinates of airfoil curvature for the whole series of NACA four digits, which is very effective in optimizing blade design. In order to get an optimal operating performance and high efficiency for the airfoil, the blade surface must be smooth and does not suffer any discontinuities or undefined cases, which cause separation of the boundary layer during the airflow, and get as a result great energy losses. Therefore, the conditions for the continuity of the blade was extracted using mathematical analysis, so the air flow does not suffer any interruptions which reduce the efficiency. This enable us to determine the locations of the maximum thickness of the blade sections on the chord along the blade, in addition to specifying conditions for the chord line length at the root and at the end of the blade which keep the blade curvature continuous and doesn’t have any irregular points, which also facilities writing the necessary programs.
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Kaya, Mustafa, and Munir Elfarra. "Effect of taper modification on the performance of NREL VI wind turbine blade for low and mid wind speeds." Wind Engineering 43, no. 4 (June 24, 2019): 392–403. http://dx.doi.org/10.1177/0309524x19858254.
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The taper distribution along the span of the NREL phase VI rotor blade is modified using a new approach. The taper distribution in this approach is expressed as a cubic spline defined by three chord lengths values in the spanwise direction: root, mid-span and tip. Then, the effect of the modified taper distribution on the thrust and the torque is studied. Various blade geometries are generated using different chord length values on the root, mid-span and tip locations while the planform area is kept fixed as the original blade, NREL VI. The flowfields are calculated using a commercial Reynolds averaged Navier–Stokes solver. The k-epsilon turbulence model is used to calculate the eddy viscosity. The computations are carried out for three different wind speeds: 5, 7 and 9 m/s. Increasing torque and decreasing thrust cases are observed. It is noticed that torque increases when the tip chord length is about one-fifth of the root and mid-span chord lengths. The thrust is decreased, as the root chord is much longer than the mid-span and the tip chord.
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GAO, Limin. "Influence of Blade-root Fillet on Transonic Rotor Performance." Journal of Mechanical Engineering 52, no. 20 (2016): 137. http://dx.doi.org/10.3901/jme.2016.20.137.
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Liu, Donghuan, and Xinchun Shang. "Failure Investigation of the Wind Turbine Blade Root Bolt." Journal of Failure Analysis and Prevention 13, no. 3 (March 15, 2013): 333–39. http://dx.doi.org/10.1007/s11668-013-9675-4.
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Kubiak Sz, J., J. A. Segura, G. Gonzalez R, J. C. García, F. Sierra E, J. Nebradt G, and J. A. Rodriguez. "Failure analysis of the 350MW steam turbine blade root." Engineering Failure Analysis 16, no. 4 (June 2009): 1270–81. http://dx.doi.org/10.1016/j.engfailanal.2008.08.015.
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